Indexed memories in general serve as storages for various indexed lists. An entry in an indexed list consists of one or more fields. A typical feature of indexed lists is that the entries contained therein may be arranged and retrieved in a certain order, according to the ascending or descending values of a certain field which has been selected as the index field for the entries in the list.
A typical example of an indexed list stored in the memory of an electronic device is the list of names, telephone numbers and potentially other associated information which is stored in the memory of a mobile telecommunication device such as a mobile phone. The user of the mobile telecommunication device needs frequently to access the list of stored entries in order to find the telephone number of the intended recipient of a call. The stored entries have most often only three fields, namely the NAME field, the TELEPHONE—NUMBER field and the MEMORY LOCATION NUMBER field. Additional fields may include fields like ADDRESS, SECOND—TELEPHONE—NUMBER etc. The NAME field is usually selected as the index field.
FIG. 1 illustrates a conventional method of accessing the entries in a list through the use of alphanumeric keys and arrow keys. Only the contents of the NAME fields are shown. Operation begins when the user presses a certain key, which in this example is the “2abc” alphanumeric key. The first entry in the ascending order of the value in the index field is shown. If the user presses the “2abc” alphanumeric key again, the first entry beginning with B is shown, and a third press on the “2abc” alphanumeric key shows the first entry beginning with C. If, at some step of operation, the user presses the “3def” alphanumeric key once, the first entry beginning with D is shown. At any step of operation pressing the arrow down key gives the immediately following entry in the ascending order of the value in the index field. Some “arrow down” indications are omitted in FIG. 1 to preserve graphical clarity (for example pressing arrow down at ARN ELISABETH leads to BERNSTEIN LEONARD although this is not illustrated in FIG. 1).
The known method of retrieving entries from the list does not come without drawbacks. As an example we may consider a situation where the user has stored the number of an emergency exchange under the name “EMERGENCY”. Additionally the user has stored a large number of other entries where the value in the NAME field begins with the letter E which is immediately followed by another letter which is before M in the alphabet. In order to retrieve the number of the emergency exchange the user has to initiate the retrieval of entries, press two times the “3def” key and press the arrow down key for a large number of times. In an urgent situation such a complicated sequence of key presses may confuse the user and cause unnecessary loss of time.